In recent years, High Definition Multimedia Interface (HDMI) has been widely used as a digital interface for connecting consumer electronic (CE) apparatuses, and has become the de facto industry standard. According to the current HDMI standard, power can be supplied from a source apparatus to a sink apparatus through a power supply line (see, for example, Patent Literature 1). The current HDMI standard specifies that the power supply (+5 V terminal) from a source apparatus to a sink apparatus is up to 5 V and 55 mA, assuming that the main purpose is to read an EDID ROM in a sink apparatus in the standby state through a DDC line.